This article is from the Bicycles FAQ, by Mike Iglesias with numerous contributions by others.
Pamela Blalock firstname.lastname@example.org
Most production bikes are built proportionally for the AVERAGE MAN.
But the average man tends to be taller than the average woman, so
women, especially smaller women, may have a much more difficult time
finding a bike that fits. Using the old guidelines of sizing a bike by
straddling the top tube may leave you a bike with a top tube that is
too long, since many of these smaller bikes have shorter seat tubes,
but the top tubes are left at the same length as larger bikes, so the
bike is no longer scaled proportionately. Of course this is not
strictly a woman's issue, but one that all smaller riders face.
Empirical evidence has come to suggest that many women are more
comfortable with a shorter top tube - stem combination than men.
Originally it was theorized that this was due to women having longer
legs and shorter torsos than men of the same height. Statistics have
proven otherwise. But despite the similar proportions, many women
still felt stretched out on bikes that men of the same size felt
comfortable on. There is no one definitive explanation for this. Some
have proposed that women may bend from the waist while men pivot more
at the hips, which would explain why two riders with identical torso
lengths might still want different top tube stem lengths. Georgena
Terry has observed that women tend to sit further back on their
saddles than men, which she believes is due to different distributions
in muscle mass. Again this could lead to that stretched out feeling.
I struggled for the longest time to get comfortable on a bike. I always
wanted to sit further back than I could. I finally found a gadget that
I could use to mount my saddle further back on the seat post. This
really helped. What helped even more was when I switched to a softride
bike. I switched for comfort, but discovered a very pleasant benefit,
that with the 5 inch range (fore/aft) of saddle adjustment along the
flat part of the beam, I could effectively choose any seat tube angle
I wanted. I could finally get my saddle far enough back.
A riding position that leaves the rider too stretched out can cause saddle
pain. It is not necessary to run out and buy a new bike right away if the
top tube on your current bike is too long. Using a shorter stem on a this
bike MAY give you a more comfortable reach. Very short stems, less than 40
mm, are available, but may have to be specially ordered.
Some shops use a fitting system called the Fit Kit. The numbers
generated from the Fit Kit are just guidelines and may not work for
everybody, especially women, since most of the original data was
collected for men. It is important to RIDE your bike and make
adjustments to achieve a perfect fit. Others may use an infinitely
adjustable stationary bike. One has been developed by Ben Serotta to
help choose the perfect size bike - whether it is a Serotta or not.
Adjustable stems are available to help you and the shop pick a perfect
length stem the first time, rather than the expensive trial and error
method of buying different length stems repeatedly until you find the
right size. Unless your current bike is a really, really poor fit, you
should be able to make a few relatively inexpensive changes to improve
the fit. Then when upgrading or buying a new bike, use what you have
learned to buy a bike that fits better.
Some builders tried to shorten the top tube by increasing the seat tube
angle, which then may place the rider uncomfortably far forward over the
pedals. This forces the rider to use an adapter in the seat post to get the
saddle back, which counteracts the *shorter* top tube. A steep seat tube
angle may be good for a time trial or triathlon, but is not comfortable for
longer distances, recreational riding or touring. And if it is true that
women tend to be more comfortable sitting further back, then this is really
A sloping top tube has been used by many manufacturers to achieve a shorter
seat tube and more standover clearance, but this leaves the top tube length
the same as that for a larger bike, so the smaller rider still feels
streched out on a somewhat out of proportion bike..
Several manufacturers have started building bikes proportionally sized for
smaller riders to specifically address those needs. There are several
different ways of getting the smaller geometry. Some bikes have a small 24"
wheel in front and a 700C or 26" wheel in back, others have two 26"or 650C
wheels. To truly scale down a frame keeping it in proportion, it is
necessary to go with smaller wheels.
To avoid confusion, let me state that by 26", I am referring to 559mm bead
seat diameter. This size wheel is most commonly used in mountain biking.
Thanks to mountain bikers use of very narrow rims, and a few tire
manufacturers willingness to make narrow, slick tires for this size, these
wheels can be used to build smaller bikes with proper proportions. Several
manufacturers make 1.25 high pressure slicks which are very nice for loaded
touring or casual riding. Specialized has the ATB turbo, which they
advertise as 1 inch wide. I am currently using these on my commuter in good
weather. And I understand from recumbent riding friends that other 26X1"
tires are available through 'bent specialty shops. While the selection of
narrow tires is somewhat limited, it is growing. I understand there is more
variety in Germany, and soon both Ritchey and Continental will have narrow
tires available in the US market.
By 650C, I am referring to wheels with a bead seat diameter of 571mm. These
wheels have found their way onto many triathlon bikes. These wheels are
also occasionally referred to as 26" wheels, which is why the bead seat
diameter number is so important. Tires for these two different *26 inch*
wheel sizes are NOT interchangeable, and it is very important to know which
one you have. Currently there is a very narrow range of tires available for
this wheel size, and I mean narrow in more ways than one. In the US, the
widest available tire is a Continental 23 or Michelin 20. In my opinion,
neither of these tires is really wide enough for general purpose use on
rough roads, and definitely not quite up to touring standards. Of course I
live in New England where road surfaces are quite rough. I have used wheels
of this size on a softride equipped bike. I don't believe I could take the
shock from such a skinny tire on a non-suspended bike, at least not for
700C is of course ISO 622, and is the most common wheel size for road bikes
in the US today.
In addition to a shorter top tube, women's bikes may also have smaller
brake levers, narrower handlebars, shorter cranks and wider saddles.
Georgena Terry was the pioneer in this area, but many other manufacturers
now build women's bikes. They may cost a little more than a comparably
equipped man's bike, due to higher production costs for fewer number of
parts. But, I believe that the extra initial cost to get a properly fit
bike will pay off in the long run, since you will either stop riding an
uncomfortable or poorly fitting bike, or you will eventually replace the
poorly fitting parts at additional cost.